Discharging cellulosic fibrous material in bulk form



Sept. 8, 1964 3,147,883

DISCHARGING CELLULOSIC FIBROUS MATERIAL IN BULK FORM K. F. o. JAKOBSON Filed April 8. 1960 United States Patent 3,147,883 DISCHARGING CELLULOSIC FIBROUS MATERIAL IN BULK FORM Kari Folke Olof .lakohson, Roslags Nasby, Sweden, as-

signor to Aktiebolaget A. Ekstroms, Maskinaiiar, a

Swedish joint-stock company Filed Apr. 8, 1960, Ser. No. 20,868 Claims priority, application Sweden Apr. 9, 1959 1 Claim. (Cl. 2221) This invention relates to a method of discharging cellulosic fibrous material, such as bagasse, esparto grass, straw and mechanical or chemical cellulose pulp in bulk form with a dry content preferably exceeding 30% and a device for carrying out the method.

It is known to discharge for example wood chips from rectangular or circular containers or silos of various types by means of discharge devices disposed in the lowermost portion of the containers or forming the bottom of the same. Said known discharge devices may be bottom gates to be opened, rotary, plane or conical bottoms provided with scraper means, scraper means travelling across the bottom of the container towards an opening in the container wall, or screws which may be stationary or travelling laterally over a stationary bottom, etc.

Said known devices of conventional type have in common that the material to be stored, for example wood chips, is fed into the uppermost portion of the container and discharged from the lowermost one. The aforementioned devices cannot be applied when the cellulose pulp is to be stored in a bulky state, because owing to its structure the pulp has a tendency to stick and to form bridges across the container section. Furthermore, in the case of forced discharge through an opening, the pulp easily forms hard and large clods blocking the discharge screws owing to the fibrous and sticky nature of the clods and their great inner cohesion.

As a characteristic feature of the containers comprising the aforementioned devices can be mentioned that the containers are rather high in relation to the bottom area. Consequently, the material forms high piles exercising a rapidly increasing pressure on the bottom so that the bulk density of the material comprised in the bottom layer is considerably higher than that of the material comprised in the upper layer. Hereby the discharge of the material is rendered ditlicult. Moreover, the constructional design of the containers does not allow the inside inspection of a container, which is a considerable disadvantage, particularly in winter time when the material and particularly its higher compressed parts are subjected to the risk of freezing. In the case of freezing, the discharge of the material is rendered impossible because the material cannot be broken into pieces nor be disengaged. The aforesaid drawbacks are eliminated by the present invention.

The method according to the invention is characterized in that the fibrous material in the form of a coherent block is directed towards a pocket disposed below the one end of the container in such a manner that the front end portion of the block breaks oil and falls down into said pocket whereafter the material is discharged by means of an elevator. The pulp is preferably advanced upwardly on said elevator.

The apparatus according to the invention is characterized in that one end wall of the container is left out and 3,147,883 Patented Sept. 8, 1964 that the bottom of the container is provided with conveying means for advancing the coherent block of fibrous material to the open end of the container below which a pocket connected to an elevator is disposed, said elevator preferably extending in an inclined upward direction from the bottom of said pocket. The pocket may be provided with a sensing device controlling the supply of the fibrous material. Means for giving the material discharged a definite thickness may be provided at the upper end portion of the elevator. At the end wall of the elevator adjacent to said open end wall, there are preferably disposed means for scraping and evening the upper portion of the fibrous material advanced in the container.

An embodiment of the apparatus according to the invention for discharging cellulose pulp from a storage container is illustrated on the accompanying drawing, the figure showing a longitudinal section through the device.

The pulp in bulk form is fed by means of a belt conveyor or from an overlying container at the one end of a longitudinal and upwardly open storage silo 1, the bottom of said silo 1 consisting of an apron conveyor 2 advancing the pulp in the form of a block towards the other, entirely open end side of the silo 1. Below said open end side of the silo a dosing pocket 3 is provided from which an elevator 4 extends in an upwardly inclined direction. When the pulp reaches the open end side of the silo and is advanced over the end roller 5 of said conveyor 2, the front end portion of the pulp block breaks and falls down into the pocket 3 from Where it is conveyed by the elevator 4. A sensing device 6 arranged in said pocket 3 interrupts the motion of the conveyor 2 as soon as the indicator is entirely covered by pulp and starts again said conveyor 2 when the indicator means has become free of pulp. If said interruption of the conveyor motion would not occur, the pulp would be pressed with such a force against the elevator 4 that there would be either stoppage or uncontrollable discharge. A perforated conveyor 7 disposed at the inlet of the silo 1 is provided with carriers, for example chains scraping over the formed pulp top and flattening the same so that the pulp may be fed into the silo even if the conveyor 2 is out of function. By means of an equalizing roller, for example a roller 8 with spikes or the like, attached to the upper portion of said elevator 4, the pulp layer on the elevator is flattened in such a manner that the pulp always is discharged with a constant thickness and that the surplus material falls down towards the pocket 3. Said roller 8 is vertically adjustable for controlling the discharge quantity, said quantity also being variable by varying the speed of the elevator.

It is obvious that the bottom of the silo need not consist of an apron or belt conveyor, as indicated in the drawing, but that the silo may be provided with a stationary bottom with carrier means mounted therein advancing the fibrous material towards the open end side of the silo.

According to the quality of the fibrous material and its corresponding angle of repose, the indicating means 6 may be arranged at different places in the pocket so that a suitable quantity of the fibrous material remains in the pocket before the next dosage reaches the pocket.

What I claim is:

The method of forming a coherent block of cellulosic fibrous material into an attenuated layer of said material 3 4 which comprises supporting said block of material on a of said pocket at a high angle to allow excess material substantially horizontal surface, periodically moving said of said layer to fall back into said pocket. block toward an edge of said surface so as to cause portions of said block to break off from said block and fall References Clted the file of this Patent down into a pocket below said edge of said surface, regu- 5 UNITED STATES PATENTS lating the rate of movement of said block toward said 2,920,355 Clark Jam 12, 1960 edge inversely in accordance with the quantity of said material contained in said pocket, and lifting a layer of FOREIGN PATENTS the material at one side of said pocket upwardly and out 850,428 France Sept. 11, 1939 

